This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A250278 #6 Jul 23 2025 12:16:41 %S A250278 8,27,52,89,140,207,288,389,504,639,780,949,1132,1335,1552,1789,2048, %T A250278 2339,2636,2957,3292,3639,4000,4401,4840,5299,5772,6265,6772,7319, %U A250278 7880,8477,9080,9711,10364,11061,11772,12495,13232,14013,14816,15647,16484 %N A250278 Number of length 3+1 0..n arrays with the sum of the squares of adjacent differences multiplied by some arrangement of +-1 equal to zero. %C A250278 Row 3 of A250277 %H A250278 R. H. Hardin, <a href="/A250278/b250278.txt">Table of n, a(n) for n = 1..201</a> %e A250278 Some solutions for n=6 %e A250278 ..4....1....4....4....2....6....5....3....5....1....2....1....1....5....6....5 %e A250278 ..4....1....6....0....1....0....2....0....1....6....1....1....2....2....3....5 %e A250278 ..1....1....6....4....2....6....5....3....6....1....1....3....1....6....6....6 %e A250278 ..4....1....4....4....2....6....5....3....3....1....2....1....1....1....6....5 %K A250278 nonn %O A250278 1,1 %A A250278 _R. H. Hardin_, Nov 16 2014